Approximately 7% of patients undergoing percutaneous coronary intervention (PCI) experience contrast induced nephropathy (CIN).¹ In patients with advanced kidney disease the incidence increases to around 30%^1,2.  CIN has been strongly associated with adverse clinical outcomes, including death, need for haemodialysis, increased hospital costs and lengths of stay.^1-6 The ratio of the contrast media (CM) volume used to the creatinine clearance is one of the strongest predictors of development of CIN following PCI.^7,8 Therefore, in order to reduce the incidence of CIN it is important to focus on strategies to reduce the volume of CM used particularly in those with chronic kidney disease (CKD).CIN continues to be a relatively common complication following PCI and fear of this complication leads to the underutilization of PCI in high-risk coronary patients with CKD. Checklists and “time out” are widely adopted in cardiac catheterisation laboratories and often incorporate a measure of the patient’s renal function. However, use of CM varies greatly between individual operators and cardiac catheterisation laboratories. To date there had been no study assessing whether incorporating a maximum target for CM witch should be not exceeded during PCI into the “time out” checklist and tracking this during the procedure would help to reduce the volume of CM used. Our study is the first to assess this. The aim of the study – is  to assess whether addition of a target for maximum contrast volume (CV) for the procedure tailored to the patient’s renal function at the time to the pre-procedure checklist during “time out” would reduce the contrast volume use during interventional coronary procedures.

A “Low Contrast Volume Protocol” was established in our catheterisation laboratory. It includes patient’s renal function described as a serum creatinine level in mkmol/l and calculated creatinine clearance (CrCl). CrCl was calculated with the Cockroft-Gault equation⁹. Based on the most relevant clinical data^7-8 two contrast volume targets were calculated: the maximal recommended to use CV and a CV witch should strictly not be exceed.  The maximal recommended to use CV was calculated according to the CrCl by the formula – CrCl X3.0 – it shows the amount of maximal recommended to use CV in mls and a CV witch should strictly not be exceed during the procedure is calculated by the formula CrCl X3.5 – it indicated the amount of the CV in mls witch is maximally allowed to use. It was a single centre prospective study, it was approved by local Bioethics committee. Patients undergoing angiogram or scheduled PCI or angiogram followed by PCI were included. Patients of a control group were included before introducing “Low Contrast Volume Protocol”, all the interventional procedures for them were performed without counting and announcing maximal targeted CV. After incorporating the “Low Contrast Volume Protocol” into routine catheterisation laboratory practice, patients were involved prospectively and maximal recommended to use and CV which is not allowed to exceed were announced during “time out” and monitored during the procedure.  The following criteria were evaluated: patient age, sex, body mass index (BMI), concomitant diseases (arterial hypertension (AH), diabetes mellitus (DM), diagnosed coronary artery disease (CAD), CKD, creatinine level, CrCl, type of interventional procedure performed, CM volume used.  Statistical analysis was performed. Numerical values were expressed as mean standard deviation or median (interquartile range) as appropriate, whereas categorical variables were expressed as percentages. All statistical analyses were performed patient-wise. Statistical significance was always set at a two-tailed probability level of less than 0.05. All statistical analyses were carried out using SPSS Statistics version 22 (IBM SPSS Inc.).

A total of 519 patients undergoing angiogram or PCI or angiogram followed by PCI on the same procedure were involved into the study. 
For 312 patients interventional procedures were performed without applying “Low Contrast Volume Protocol”. The mean age was 71.0 ± 12.1 years. There were 67.3% male and 32.7% female patients.  Comorbidities included as followed: AH (93.3%), Dyslipidaemia (91.7%) and CAD (97.1%). Nearly one fifth (18.3%) had DM and 21.8% had diagnosed CKD. For 12.8% of patients diagnostic angiogram was performed, 10.0% underwent scheduled PCI, the majority of patients 77.2%.For 207 patients the “Love Contrast Volume Protocol” was applied, maximal recommended CV amounts were personally calculated based on their kidney function, contrast dosing was actively monitored during the procedure.  The mean patient age was 68.2 ± 11.0 years. There were 58.5% male and 41.5% female patients.  Comorbidities included: AH (96.1%), Dyslipidaemia (88.9%) and CAD (99.5%). Nearly one fifth (19.8%) had DM and 19.3% had diagnosed CKD. For 29.0% of patients diagnostic angiogram was performed, 14.5% underwent scheduled PCI, 56.5% underwent angiogram and PCI. A comparison of CM volume used between both groups revealed that in the “Low Contrast Volume Protocol” arm where maximal recommended CM amount was calculated and CM usage during the procedure was observed, the amount of used contrast was significantly reduced 192.5 ± 71.9 mls vs. 104.5 ± 51.7  mls (p<0.001).The same results were revealed in angiogram, PCI and angiogram followed by PCI subgroups. For the patients whom diagnostic angiogram was performed, the used amount of contrast was reduced nearly by third 93.8 ± 36.6 mls vs. 61.7 ± 29.0 mls (p<0.001). In scheduled PCI subgroup mean contrast volume was reduced by 45.0% when the protocol was applied, 183.9 ± 52.1 vs. 102.2 ± 36.9 mls (p<0.001). In the subgroup there angiogram and PCI was performed mean contrast volume usage was reduced by nearly 40.0%, 210.0  ± 64.8 mls vs. 127.2  ± 49.8 mls (p<0.001).

Our applied personalised maximal recommended to use CM volume calculation leads to significant reduction in contrast volume usage and  risk reduction of contrast induced kidney injury development.